A substantial portion of a nut harvesting industry now uses a nut shaker called a "Monoboom" shaker for shaking nuts from nut trees. The nut shaker is usually mounted on a tractor with a boom section extending forwardly in the direction of travel with two shaker head support arms having sleeves pivotally and rotatably mounted on a laterally extending rod fixed to the boom section in perpendicular relation thereto. The support arms extend forwardly in the direction of travel and support a shaker head by rubber mountings. Piston and cylinder assemblies interconnect the boom section and the support arms in order to elevate the forward ends of the arms and the shaker head mounted thereon in order to position the shaker head so that a pair of jaws may grip the nut tree to be shaken. Each jaw includes a shaker pad and supporting slings mounted thereon which grip the tree. The above described structure and the manner of use of the existing nut shaker is conventional and well known.
Shaker pads and slings which support the shaker pads become quite hot from frictional heating when operating in a normal manner in view of the gripping engagement with the nut tree and relative movement between components of the shaker head including the shaker pad and slings. This problem has been alleviated by the periodic exchange of hot shaker pads for cool pads and lubricating the surfaces of the slings by the use of a lubricant which is placed on the slings when the pads are being interchanged. The replacement of the pads and greasing of the slings is required generally on an hourly basis and it requires approximately ten minutes to replace the pads, grease the slings and return the nut shaker to operative condition for another cycle.
U.S. Pat. No. 4,893,458 issued Jun. 16, 1990 for Liquid Cooled Shaker Pad Retaining Sling discloses one effort that has been made to reduce the operating temperature of the shaker pad and slings. In this patent, the sling surfaces are provided with passageways and connected with supply and return lines by which a coolant can be circulated through the sling pad structure and returned to a reservoir.